Sequence variability of the pattern recognition receptor Mermaid mediates specificity of marine nematode symbioses
Sequence variability of the pattern recognition receptor Mermaid mediates specificity of marine nematode symbioses
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DOI：
10.1038/ismej.2010.198
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发表时间：
2011-06-01
期刊：
影响因子：
11
通讯作者：
Ott, Joerg A.
中科院分区：
文献类型：
--
作者：
Bulgheresi, Silvia;Gruber-Vodicka, Harald R.;Ott, Joerg A.
宿主选择特定的微生物伙伴是一个非常重要的过程。它保证了高度特异性的共生关系在宿主世代中持续存在。海洋线虫 Laxus oneistus 的角质层被单一种系的硫氧化细菌覆盖。它们嵌入宿主分泌的粘液层中，其中含有甘露糖结合蛋白“美人鱼”。这种 Ca2+ 依赖性凝集素介导共生体聚集和线虫附着。在这里，我们发现 Stilbonema majum（一种与 L. oneistus 共生于浅水沉积物中的共生线虫）所覆盖的细菌在系统发育上与覆盖 L. oneistus 的细菌不同。美人鱼 cDNA 分析揭示了两种线虫物种中广泛的蛋白质序列变异性。我们表达了三种重组美人鱼亚型，它们基于结构预测显示出最不同的碳水化合物识别域（CRD）。我们表明，三种 CRD（DNT、DDA 和 GDA 类型）对 L. oneistus 和 S. majum 共生体具有不同的亲和力。特别是，仅由 S. majum 表达的 GDA 类型对其共生体表现出最高的凝集活性，对其共生体 L. oneistus 表现出最低的凝集活性。此外，在 GDA 类型中孵化 L. oneistus 不会导致共生体完全脱离，而在其他类型中孵化则会导致共生体完全脱离。这表明线虫表面上特定美人鱼亚型的存在在特定共生体的附着中发挥作用。这是关于微生物相关分子模式受体中序列变异在有益关联中的功能作用的第一份报告。 ISME 杂志 (2011) 5, 986-998; doi：10.1038/ismej.2010.198；在线发表 2011 年 1 月 13 日 主题类别：微生物-微生物和微生物-宿主相互作用
Selection of a specific microbial partner by the host is an all-important process. It guarantees the persistence of highly specific symbioses throughout host generations. The cuticle of the marine nematode Laxus oneistus is covered by a single phylotype of sulfur-oxidizing bacteria. They are embedded in a layer of host-secreted mucus containing the mannose-binding protein Mermaid. This Ca2+ -dependent lectin mediates symbiont aggregation and attachment to the nematode. Here, we show that Stilbonema majum-a symbiotic nematode co-occurring with L. oneistus in shallow water sediment-is covered by bacteria phylogenetically distinct to those covering L. oneistus. Mermaid cDNA analysis revealed extensive protein sequence variability in both the nematode species. We expressed three recombinant Mermaid isoforms, which based on the structural predictions display the most different carbohydrate recognition domains (CRDs). We show that the three CRDs (DNT, DDA and GDA types) possess different affinities for L. oneistus and S. majum symbionts. In particular, the GDA type, exclusively expressed by S. majum, displays highest agglutination activity towards its symbionts and lowest towards its L. oneistus symbionts. Moreover, incubation of L. oneistus in the GDA type does not result in complete symbiont detachment, whereas incubation in the other types does. This indicates that the presence of particular Mermaid isoforms on the nematode surface has a role in the attachment of specific symbionts. This is the first report of the functional role of sequence variability in a microbeassociated molecular patterns receptor in a beneficial association. The ISME Journal (2011) 5, 986-998; doi:10.1038/ismej.2010.198; published online 13 January 2011 Subject Category: microbe-microbe and microbe-host interactions